HELP Accused of fraudulent mileage claim falsely

[Madwelshie]

Please help.......
Someone has falsely reported myself and a colleague to an area manager(not my direct superior) for sharing a car to travel to work in her area but fraudulently claiming mileage individually. I believe the accusations were made by text message and we were both named directly however I have not been told that officially. The recipient of the message has contacted my area manager who has then asked us individually if we travelled alone and we have both independently stated that we did because it is the truth.. We were asked in general conversation, not as part of any official investigation however when I spoke to my AM later in the day I queried why he had asked because his manner seemed very odd.. His response to my question was to say “why do you think i’m Asking” and he has then confirmed my assumption that some kind of accusation had been made.
I have had issues in the past with the area manager that received this message and I have been told(again unofficially) that she will push this as far as she can and she is already talking of sacking us both. There is no possible way I can disprove the accusation as I was the only person in my car, the chance of someone I know randomly spotting me driving in a town 70 miles from my home is almost non-existent and even if I was seen arriving home alone it is irrelevant as my colleague lives in a town between my own and the workplace.
I’m devastated, I’ve worked in the same industry for over 20 years, only ever worked for 3 companies in all that time, left my original job for a promotion at a different company and only left them when I was forced to relocate back to my childhood home due to pregnancy. I’ve been with my current employer for nearly 9 years and have an exemplary record with them and I can’t believe this is happening.
What should I do?
Do we have the right to see this message accusing us?
Should the company search through company records to find the phone number that sent the message to identify the accuser?
if they are identified do we have the right to know who has accused us?
If the company decide to believe us do we have grounds to raise a grievance against our accuser?
if they cannot identify the source, do we have grounds to raise a grievance against the area manager that has pushed this through the disciplinary procedure based on a single anonymous message(the company won’t find any evidence of wrong doing for the same reasons I can’t prove I am innocent) and her personal feelings towards me? Any advise would be very much appreciated

[ULA]

At the moment what is the situation - has the company written to confirm that they are undertaking an investigation as a result of allegations of you fraudulently claiming mileage? That would in my opinion be the first stage of the process to establish whether or not there are grounds to instigate disciplinary action.

If as a result of any investigation they did decide to undertake disciplinary action then the company would need to provide you with all the documentary evidence they were going to rely on so you would have a chance to see any witness statements, records supporting the allegations etc. in advance of the meeting and thereby prepare your defence.

If disciplinary action is taken then as part of the process you would have a right to appeal if you did not agree with the outcome.

Employees have the right to raise a grievance if they feel that there is a genuine grievance situation. However I would suggest getting some better clarity around what is happening at the moment as it still, from what you have said, appears to be unclear and may mean that any grievance does not appropriately address the nature of your grievance.